Iris diaphragm blade



March 29, 1949.

' G. K. CZARNIKOW ET AL 2,465,578

IRIS DIAPHRAGM BLADE 2 Sheets-Sheet 1 Filed March 2, 1946 nventorarm/(0W eorge k. BB C/areHce Ric/lard V cm Horn (Ittorneg Patented Mar.29, 1949 UNITED STATES PATENT OFFICE IRIS DIAPHRAGM BLADE tion of NewYork Application March 2, 1946, Serial No. 651,557

1 Claim.

This invention relates to an iris diaphragm for use on cameras andsimilar structures, with particular reference to the type of diaphragmemploying a multiplicity of blades, each of which is pivotally connectedat one point to an operating ring and at another point to a radial slotin a fixed guide plate, as a result of which the blades are moved toopen or close the aperture when the operating ring is turned, and it hasfor its particular purpose to afford a structure in which the operatingring turns through a relatively large arc to effect travel of the bladesfrom closed to open position.

In diaphragms as heretofore constructed, the operating ring turnsthrough approximately onesixth of its circumference to effect movementof the blades from one extreme position to the other, such relativelyshort movement of the operating rin necessitating a correspondinglysmall indicating scale on the adjusting ring, and it is a purpose of theinvention to cause the operating ring to travel through a much largerarc, preferably about one-third of its circumference, whereby theindicating scale on the adjusting ring is much larger and more legiblethan in conventional diaphragms.

Another purpose of the invention is to afford a structure whereby thespacin between the several indications of the scale on the adjustingring can be readily controlled and made more nearly uniform by varyingthe contour of the aperturedefining edge of the blade so as to provideany desired spacing between the intermediate indications of the scalerepresenting different positions of the blades and different sizedapertures.

More specifically, the invention has for its purpose to afford astructure of diaphragm blade that gives a different ratio of changebetween the size of the aperture and the circumferential movement of theadjusting ring, thus reducing the amount of error and increasin thetolerance permitted, as compared with prior devices where the change inthe size of the aperture is directly proportionate to the extent ofmovement of the adjusting ring.

Another object of the invention is to afford a construction of diaphragmblade designed to operate as set forth above, which is simple andeconomical to produce and assemble, and is practical,

efficient, and durable under actual operating conditions.

Still a further purpose is to afford a diaphragm having a minimum numberof blades capable of the required adjustments, and in which the bladesare constructed so as to cooperate in a practical and efficient mannerin all positions.

To these and other ends, the invention consists in the construction andarrangement of parts that will appear clearly from the followingdescription when read in conjunction with the accompanying drawings, thenovel features being pointed out in the claim following thespecification.

In the drawings:

Fig. 1 is a view in side elevation of a diaphragm housing and adjustingring constructed in accordance with a preferred embodiment of theinvention;

Fig. 2 is a vertical sectional view of Fig. 1;

Fig. 3 is a view in end elevation of the structure, looking toward thefixed slotted guide plate;

Fig. 4 is an end elevation looking in a direction opposite to Fig. 3,and showing the operating ring;

Fig. 5 is a transverse sectional view on line 5-5 of Fig. 2, showing thediaphragm blades in closed position, and the concealed portion of oneblade indicated in dotted lines;

Fig. 6 is a similar view showing the diaphragm blades in open position,with the concealed portion of the same blades as in Fig. 5 shown indotted lines, and

Fig. 7 is a diagrammatic view illustrating the relative movement betweenone diaphragm blade and the indicatin scale as the blade moves from itsextreme open to its extreme closed positions.

Referring more particularly to the drawings in which like referencenumerals refer to the same parts throughout the several views, ldesignates a housing that is attached to the wall of a camera as usual,and 2 is an adjusting ring threaded on the housing I and provided withan indicating scale 3 for an f/2.8 lens, showing aperture sizes from 2.8to 22. The scale 3 cooperates with an index mark d on the housing and isthreaded on the housing to permit adjustment to the extent of the scale3.

To this end, the adjusting ring 2 carries a pin on line 2--2 5 that ismovable through a slot 6 in the housin such movement being limited bythe ends of the slot 6, and the pin 5 extends into an opening in anoperating ring 7 that carries the diaphragm blades, and has anoscillatory movement in the housing to open and close the diaphragm,while 8 designates a split rin that retains the operating ring 1 in thehousing against a shoulder formed therein and against which theoperating ring turns.

The parts thus far described, with the exception of the indicatingscale, are old, but in prior types of diaphragms, the indicating scalehas been considerably smaller or approximately one-half the length ofthe indicating scale 3, due to the adjust-- ing and operating ringsturning through a relatively short are in order to actuate the bladesfrom one extreme osition to another, and this invention has to do withthe formation of the blades whereby the ratio of movement of theadjustin ring to the extent of movement of the diaphragm blades ismodified, resulting in turning of the adjusting ring through a distanceof approximately one-thircLits periphery, or from 120 to 130 if desired.This is accomplished by constructing the blades in such fashion that agiven movement of the blades in one direction or the other requires amuch greater corresponding movement of the adjusting ring, and theparticular construction of the blade whereby this is accomplished willnow be described.

Each blade is preferably of the general shape illustrated in Fig. '7,and includes an outwardly widening supporting portion 9, pivoted at illto the operating ring 1, a narrow central portion 1 I, and an outwardlywidening end portion l2 extending generally in a right-angular directionto the supporting portion 9 and has a pivotal con-- nection I3 slidablein one of the radial slots I4 in the stationary guide plate is which issecured in or forms a part of the housing, as usual in this type ofconstruction. Between the supporting portion 9 and the end portion l2 ofthe blade, the latter is provided with a generally V-shaped recesshaving along one side an aperture-defining edge that when in closedposition extends in a general direction toward the pivotal connection l3or its path of travel, and transversely of a straight line passinthrough the centers of the pivotal connections I!) and E3. Thus the twopivotal connections l and i3 form approximately a right-angled trianglewith the apex of the V- shaped recess located therebetween.

In the specific structure shown, the aperturedefining edge includes astraight portion it at the center which cooperates with the other bladesto vary the size of the opening within the range indicated, andterminates in a straight portion l1 arranged at a slight angle to thecentral portion l6 and functioning to define the larger apertures. Thedisposition and relation of the aperture-defining edges l6 and I! may bevaried as desired to establish the desired spacing between the severalmarkings on the indicating scale and to vary the amount of movement ofthe blade required to adjust from fully open to fully closed positions,and the aperture-defining edge i6 is located so that at any giveninstant in the movement of the blade, it is nearly parallel to thedirection of movement of the aperture-defining edge. As the blade movesto open or closed position, the aper ture-defining edge [6 has acombined movement in two directions, namely, endwise of itself andtransversely of the aperture so that the effective movement of the edgeIt in closing the aperture is proportionately much less than the arcuatemovement of the operating and adjusting rings. The same conditionapplies to the edge I! which is adjacent to the edge l6 and functionsafter the latter has moved beyond the aperture, and at the extremity ofedge [7, the blade includes an inwardly extending, preferably pointednose l8 that insures proper overlapping relationship and movement of theblades in all positions.

In diaphragms as heretofore constructed, the aperture is opened andclosed by movement of blades in direct proportion to the arcuatemovement of the adjusting ring, whereas with this invention, owing tothe form of the blade and the disposition of the aperture-defining edgein relation to the pivotal connections of the blade, a considerablygreater movement of the aperturedefining edge is required between theextreme open and closed positions. Consequently a greatly increasedarcuate movement of the adjusting and operating rings takes place toeffect movement of the blades from open to closed position.

This is illustrated diagrammatically in Fig. 7 in which, for the sake ofclarity, the blade is shown as turning around the pivotal point l0, andthe successive positions of the end portion 12 are illustrated as movingfrom closed to open position in relation to the indicating scale. It isto be understood that in the actual mechanism, the pivotal point I3moves radially in a slot M, as shown in Figs. 3, 5 and 6, and the pivotIll moves bodily with the operating ring from the position shown in Fig,5 to that illustrated in Fig. 6, but the movement of the blade inrelation to the scale on the adjusting ring is as shown in Fig. '7, withthe ring turning through an arc of more or less while the blade isoperated from one extreme position to the other.

Fig. 5 illustrates the diaphragm with the blades in closed position,showing the concealed portion of one of the blades in dotted lines, andFig. 6 shows the same blade partially in dotted lines after thediaphragm has been operated to open the aperture to its maximum size.The slidable pivotal connection I3 has moved inwardly in a straight linefrom the position shown in Fig. 5 while the operating ring 7 has turnedto move the pivotal connection IE3 from its lower position of Fig. 5 toits extreme upper position shown in Fig. 6.

While the invention has been disclosed in connection with a particularconstruction, it is not restricted to the details herein shown, andthisapplication is intended to cover such modifications or departures asmay come Within the purposes of the improvement and the scope of thefollowing claim.

We claim:

An iris diaphragm blade comprising an elongated fiat body having twopivot points near opposite ends of the body and having an eiiective edgecooperating with the efiective edges of other similar diaphragm bladesto define a diaphragm aperture, one of said pivot points being mountedat a fixed distance from the center of such aperture, the other of saidpivot points being at a variable distance from the center of suchaperture; said effective edge starting at a point approximately midwayof the length of the body and. materially, oirset laterally to one sideof a straight line joining said two pivot points, thence.

extending in a series of approximately straight line segments, the.first segment pointing approxi mately toward said variable one of saidpivot points and being oblique with respect to said straight linejoining the pivot points, an intermediate segment being oblique but at agreater angle to said straight line joining the pivot points, and aterminal segment of said effective edge lying approximatelyperpendicular to said straight line joining the pivot points, saidterminal segment extendinga material distance beyond said straight linejoining the pivot points on the opposite side thereof from said startingpoint of said efiective edge, successive portions of said efiective edgefrom the first segment to the terminal segment thereof being adapted tolie substantially tangent to successively larger apertures defined bythe diaphragm blade in conjunction with other similar blades.

GEORGE K. CZARNIKOW. CLARENCE RICHARD VAN HORN.

REFERENCES CITED The following references are of record in the file ofthis patent:

